Institute for Computational Science and Technology ICST

Thành Phố Tuyên Quang, Vietnam

Institute for Computational Science and Technology ICST

Thành Phố Tuyên Quang, Vietnam
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Duong L.V.,Institute for Computational Science and Technology ICST | Nguyen M.T.,Ton Duc Thang University
Chemical Physics Letters | Year: 2017

Partial electron localization functions ELF(σ_loca), ELF(π) and ELF(σ_delo) of boron Bn and silicon MSi12 double ring (DR) clusters were analyzed. In a DR, separated basins are localized within peripheral bonds (σ), delocalized outside inner bonds (π), or delocalized above and below peripheral bonds (σ). MO spectrum of skeleton D6h Si12 DR follows delightfully the hollow cylinder model. A mixture of different sets of MOs makes the D6h Si12 structure highly unstable. Upon interacting with 3d orbitals of Cr dopant, such a mixed behavior of MO sets is removed and the Cr@Si12 DR becomes a global minimum structure. © 2017 Elsevier B.V.


Van Duong L.,Institute for Computational Science and Technology ICST | Tho Nguyen M.,Institute for Computational Science and Technology ICST
Physical Chemistry Chemical Physics | Year: 2017

A doping of small boron clusters with silicon atoms leads to the formation of stable boron nanoribbon structures. We present an analysis on the geometric and electronic structure, using MOs and electron localization function (ELF) maps, of boron ribbons represented by the dianions B10Si2 2- and B12Si2 2-. The effect of Si dopants and the origin of the underlying electron count [⋯π2(n+1)σ2n] are analyzed. Interaction between both systems of delocalized π and σ electrons creating alternant B-B bonds along the perimeter of a ribbon induces its high thermodynamic stability. The enhanced stability is related to the self-locked phenomenon. © 2017 the Owner Societies.


Tam N.M.,Ho Chi Minh City University of Technology | Pham H.T.,Institute for Computational Science and Technology ICST | Duong L.V.,Institute for Computational Science and Technology ICST | Pham-Ho M.P.,Institute for Computational Science and Technology ICST | Nguyen M.T.,Catholic University of Leuven
Physical Chemistry Chemical Physics | Year: 2015

Stabilized fullerene and tubular forms can be produced in boron clusters Bn in small sizes from n ∼ 14 to 20 upon doping by transition metal atoms. B14Fe and B16Fe are stable tubes whereas B18Fe and B20Fe are stable fullerenes. Their formation and stability suggest the use of dopants to induce different growth paths leading to larger cages, fullerenes and tubes of boron. © the Owner Societies 2015.


Duong L.V.,Institute for Computational Science and Technology ICST | Pham H.T.,Institute for Computational Science and Technology ICST | Tam N.M.,Ho Chi Minh City University of Technology | Nguyen M.T.,Ho Chi Minh City University of Technology
Physical Chemistry Chemical Physics | Year: 2014

We determined the geometries and chemical bonding phenomena of the B 27 system in its dicationic, cationic, neutral, anionic and dianionic states using DFT computations. In both cationic and neutral states, the triple ring tubular forms correspond to the lowest-energy isomers, especially in B 27 +. The cation B27 + represents the first stable hollow cylinder having a triple ring among the pure boron clusters. In the anionic and dianionic states, the quasi-planar structures are favoured due to a charge effect. In the triple ring tube B27 +, strong diatropic responses to external magnetic field occur in both radial and tangential types of electrons, and thus confer it a characteristic tubular aromaticity. The presence of a consistent aromatic character contributes to its high thermodynamic stability. The shapes of calculated MOs of B 27 + TR can be predicted by the eigenstates of a simple model of a particle on a hollow cylinder. The number of electrons in a hollow cylinder should attain a number of (4N + 2M) with M = 0 and 1 for both radial and tangential electrons, depending on the number of non-degenerate MOs occupied, in order to properly fulfill the closed electron shells. In the case of B27 +, M = 0 for radial electrons and M = 1 for tangential electrons. © 2014 The Owner Societies.


Pham H.T.,Institute for Computational Science and Technology ICST | Duong L.V.,Institute for Computational Science and Technology ICST | Tam N.M.,Ho Chi Minh City University of Technology | Pham-Ho M.P.,Institute for Computational Science and Technology ICST | Nguyen M.T.,Catholic University of Leuven
Chemical Physics Letters | Year: 2014

Geometries and bonding of B30, B36, B40 and B42 clusters were studied using quantum chemical computations. The bowl B30 and B36 and planar B42 clusters exhibit disk aromaticity. Diatropic ring current is strong in B30 and weaker in B42. A fullerene-like B40 (D2d) having two hexagons and four heptagons was found as the lowest-lying isomer. Such a fullerene whose MOs closely mimic those of the buckyball B80, represents novel structural feature of boron clusters. The most stable B 42 (C2h) isomer is a triple ring tube with consistent σ + π diatropic magnetic responses making it a tubular aromatic species. © 2014 Elsevier B.V. All rights reserved.


Tai T.B.,Catholic University of Leuven | Duong L.V.,Institute for Computational Science and Technology ICST | Pham H.T.,Institute for Computational Science and Technology ICST | Mai D.T.T.,Catholic University of Leuven | Nguyen M.T.,Catholic University of Leuven
Chemical Communications | Year: 2014

The B30 boron cluster has a bowl rather than a double-ring or a triple-ring tubular structure. This bowl isomer exhibits disk-aromaticity similar to that found for B202- and B19 - clusters. We confirmed that the concept of disk-aromaticity can be applied to both planar and non-planar systems. This journal is © The Royal Society of Chemistry.


Tai T.B.,Catholic University of Leuven | Nguyen M.T.,Catholic University of Leuven | Nguyen M.T.,Institute for Computational Science and Technology ICST
Nanoscale | Year: 2015

In a recent paper (Nanoscale, 2014, 6, 11692), based on the results computed using DFT and MP2 methods, the all-boron fullerene I was reported to be the global minimum of the cluster B38 and was much more stable than the quasi-planar II. In this comment, we have shown that at higher level of theory CCSD(T), both structure I and quasi-planar II are almost degenerate in energy and the B38 can be considered to be of a transition size between 2D and 3D boron clusters. While the MP2 method favours the 3D structure I, the CCSD method tends to overestimate the relative stability of the 2D structure II. © 2015 The Royal Society of Chemistry.


Tai T.B.,Catholic University of Leuven | Tam N.M.,Catholic University of Leuven | Tam N.M.,Institute for Computational Science and Technology ICST | Nguyen M.T.,Catholic University of Leuven
Theoretical Chemistry Accounts | Year: 2012

We investigate the molecular and electronic structure and thermochemical properties of the cationic boron clusters B n + with n = 2-20, using both MO and DFT methods. Several functionals are used along with the MP2, G3, G3B3, G4, and CCSD(T)/CBS methods. The latter is the high accuracy reference. While the TPSS, TPSSh, PW91, PB86, and PBE functionals show results comparable to high-accuracy MO methods, both BLYP and B3LYP functionals are not accurate enough for three-dimensional (3D) structures. A negligible difference is observed between the B3LYP, MP2, and CCSD(T) geometries. A transition between 2D and 3D structures occurs for this series at the B 16 +-B 19 + sizes. While smaller clusters B n + with n ≤ 15 are planar or quasi-planar, a structural competition takes place in the intermediate sizes of B 16-19 +. The B 20 + cation has a 3D tubular shape. The standard heats of formation are determined and used to evaluate the cluster stability. The average binding energy tends to increase with increasing size toward a limit. All closed-shell species B n + has an aromatic character, but an enhanced stability is found for B 5 + and B 13 + whose aromaticity and electron delocalization are analyzed using the LOL technique. © 2012 Springer-Verlag.


Nguyen H.T.,Catholic University of Leuven | Nguyen T.-Q.,University of California at Santa Barbara | Nguyen M.T.,Catholic University of Leuven | Nguyen M.T.,Institute for Computational Science and Technology ICST
Chemical Physics Letters | Year: 2012

The molecular structures, electronic and charge-transport properties of three conjugated polyelectrolytes (CPEs) including PFPhCO 2Na, PFPhSO 3Na, and PFPhBIm 4 are studied using the density functional theory with B3LYP functional. The charge injection and charge transport properties are investigated through the ionization energies, electron affinities, lowest allowed excitation energies, reorganization energies and electron transfer integrals. The electron/hole injections have great effect on the planarity of cationic/anionic CPEs. The band gaps of the CPEs do not vary significantly with the charged groups and counterions. Charge-transport properties show that the PFPhSO 3Na and PFPhBIm 4 are good candidates for electron-transport materials. © 2012 Elsevier B.V. All rights reserved.


Tai T.B.,Catholic University of Leuven | Nguyen H.M.T.,Hanoi National University of Education | Nguyen M.T.,Catholic University of Leuven | Nguyen M.T.,Institute for Computational Science and Technology ICST
Chemical Physics Letters | Year: 2011

The coinage metal encapsulated group 14 cationic clusters X 10M+ (X = Ge, Sn, Pb and M = Cu, Ag, Au) are investigated using quantum chemical calculations. While Cu- and Au-doped clusters have similar stability, Ag-doped counterparts are less stable. The D4d global minima have large frontier orbital gaps and binding energies, and are magic clusters of 40 valence electrons that satisfy the jellium shell model. The concept of doubly spherical aromaticity, based on the number of 2(N + 1) 2 π and σ valence electrons, is proposed to account for the enhanced stability. Predictions are in good agreement with experiment for available X10Cu+ clusters. © 2010 Elsevier B.V. All rights reserved.

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